Cyclopentane

Cyclopentane

Names
IUPAC name Cyclopentane
Other names pentamethylene
Identifiers
CAS Number	287-92-3
ChEBI	CHEBI:23492
ChemSpider	8896
EC Number	206-016-6
Jmol 3D model	Interactive image
PubChem	9253
RTECS number	GY2390000
InChI InChI=1S/C5H10/c1-2-4-5-3-1/h1-5H2 Key: RGSFGYAAUTVSQA-UHFFFAOYSA-N InChI=1/C5H10/c1-2-4-5-3-1/h1-5H2 Key: RGSFGYAAUTVSQA-UHFFFAOYAL
SMILES C1CCCC1
Properties
Chemical formula	C5H10
Molar mass	70.1 g/mol
Appearance	clear, colorless liquid
Odor	mild, sweet
Density	0.751 g/cm^3
Melting point	−93.9 °C (−137.0 °F; 179.2 K)
Boiling point	49.2 °C (120.6 °F; 322.3 K)
Solubility in water	156 mg·l^−1 (25 °C)[1]
Solubility	soluble in ethanol, acetone, ether
Vapor pressure	400 mmHg (31 °C)[2]
Acidity (pKa)	~45
Refractive index (nD)	1.4065
Hazards
Main hazards	Flammable[2]
NFPA 704	3 1 0
Flash point	−37.2 °C (−35.0 °F; 236.0 K)
Autoignition temperature	361 °C (682 °F; 634 K)
Explosive limits	1.1%-8.7%[2]
US health exposure limits (NIOSH):
PEL (Permissible)	none[2]
REL (Recommended)	TWA 600 ppm (1720 mg/m^3)[2]
IDLH (Immediate danger)	N.D.[2]
Related compounds
Related compounds	cyclopropane, cyclobutane, cyclohexane
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
verify (what is  ?)
Infobox references

Cyclopentane is a highly flammable alicyclic hydrocarbon with chemical formula C₅H₁₀ and CAS number 287-92-3, consisting of a ring of five carbon atoms each bonded with two hydrogen atoms above and below the plane. It occurs as a colorless liquid with a petrol-like odor. Its melting point is −94 °C and its boiling point is 49 °C. Cyclopentane is in the class of cycloalkanes, being alkanes that have one or more rings of carbon atoms.

The typical structure of cyclopentane is the "envelope" conformation.

It is formed by cracking cyclohexane in the presence of alumina at a high temperature and pressure.

It was first prepared in 1893 by the German chemist Johannes Wislicenus.^[3]

Industrial usage

Cyclopentane is used in the manufacture of synthetic resins and rubber adhesives and also as a blowing agent in the manufacture of polyurethane insulating foam, as found in many domestic appliances such as refrigerators and freezers, replacing environmentally damaging alternatives such as CFC-11 and HCFC-141b^[4]

Multiply alkylated cyclopentane (MAC) lubricants have low volatility and are used in some specialty applications.^[5]

The United States produces more than half a million kilograms of this chemical per year.

Formulation of cycloalkanes

Cycloalkanes can be formulated via a process known as catalytic reforming.

For example, 2-methylbutane can be reformed into cyclopentane, by use of a platinum catalyst. This is particularly well known in automobiles, as branched alkanes will burn much more readily.

Half-chair conformation of lower-energy state chemical structure of cyclopentane.

References

1. Record of cyclopentane in the GESTIS Substance Database of the IFA, accessed on 28 February 2015
2. "NIOSH Pocket Guide to Chemical Hazards #0171". National Institute for Occupational Safety and Health (NIOSH).
3. J. Wislicenus and W. Hentschel (1893) "Der Pentamethenylalkohol und seine Derivate" (Cyclopentanol and its derivatives), Annalen der Chemie, 275 : 322-330; see especially pages 327-330. Wislicenus prepared cyclopentane from cyclopentanone ("Ketopentamethen"), which is prepared by heating calcium adipate.
4. Greenpeace - Appliance Insulation
5. Pennzane - lubrication technology